Computer system users, administrators, and designers (referred to herein as users) usually have a goal of highest performance at lowest cost. To achieve this goal, users typically implement a simulation to model operation of a real system to determine a cost/benefit associated with changing an operating condition associated with the real system. Conventional simulation systems (or virtual systems), however, are generally limited in that certain operating parameters associated with real systems that the simulation systems need in order to appropriately mimic operation of the real systems are unknown. For example, in a database system, the final size of a sort is only known with complete certainty only after the sort is executed. Consequently, for these unknown operating parameters, conventional simulation systems typically predict such unknown operating parameters and constrain operation of the simulation system using such predicted operating parameters (e.g., a predicted sort size in the example above). Simulating a real system based on predicted operating parameters can lead to substantially inaccurate results and, therefore, inaccurate cost/benefit analyses.
Accordingly, what is needed are techniques to more accurately simulate operation of a real system so that, for example, a more reliable cost/benefit analysis can be obtained. The present invention addresses such a need.